1. Field of the Invention
The present invention relates generally to wireless communication and, in particular, to a handover method and apparatus for facilitating a handover to a femto cell in a wireless communication system including femto and macro cells.
2. Description of the Related Art
A femto cell is a small cellular base station designed to provide short-range coverage of about 10 meters for use in a home or small business and a broadband connection to a core network. Commonly, a femto cell extends the cellular network coverage indoors, providing users with higher quality and fixed-mobile convergence services.
The 3rd Generation Partnership Project (3GPP) considers an environment in which Closed Subscriber Group (CSG) cells and legacy macro cells coexist. Typically, the terms “CSG cell”, “femto cell”, “CSG cell base station”, and “femto cell base station” are synonymously used. In a 3GPP Long Term Evolution (LTE) system, an evolved Node B (eNB) denotes the macro cell base station, and a Home eNB (HeNB) denotes a femto cell base station (or CSG cell base station).
The network architecture designed to support a femto cell enables deployment of a plurality of femto cell base stations and a User Equipment (UE) to measure the signals of the femto cell and macro cell base stations (or eNBs). For a handover between the macro cell eNBs, the UE analyzes a signal transmitted by a handover target eNB to acquire a Physical Cell ID (PCI) and sends a measurement report based on the PCI to a currently serving eNB such that the serving eNB can make a handover decision.
For a handover from a macro cell eNB to a femto cell eNB (i.e., HeNB) or from an HeNB to another HeNB, however, the network must also determine whether the particular UE is permitted to access the target HeNB. Accordingly, there is a need to develop a method for facilitating a handover of a UE to a femto cell (CSG cell or HeNB) in a wireless communication system supporting deployment of femto cells.